High Rate Systems Research Articles

Monobit digital receivers: design, performance, and application to impulse radio

Digital receivers for future high-rate high-bandwidth communication systems will require large sampling rate. This is especially true for ultra-wideband (UWB) communications with impulse radio (IR) modulation. Due to high complexity and large power consumption, multibit high-rate analog-to-digital converter (ADC) is difficult to implement. Monobit receiver has been previously proposed to relax the need for high-rate ADC. In this paper, we derive optimal digital processing architecture for receivers based on monobit ADC with a certain over-sampling rate and the corresponding theoretically achievable performance. A practically appealing suboptimal iterative receiver is also proposed. Iterative decision-directed weight estimation, and small sample removal are distinctive features of the proposed detector. Numerical simulations show that compared with full resolution matched filter based receiver, the proposed low complexity monobit receiver incurs only 2 dB signal to noise ratio (SNR) loss in additive white Gaussian noise (AWGN) and 3.5dB SNR loss in standard UWB fading channels.

The Evolution and Potential of Networked Pipe

Technology Update The need for “next-generation” technology for improved data transmission up the hole in drilling operations has been acknowledged for more than 2 decades. The term “next generation” typically implied a quantum leap in transmission speed from that available, by means of current state-of-art telemetry. That need is now filled by networked drillpipe (Figs. 1 and 2). Development of the technology began in 1997. Initial R&D addressed two problems, the growing need for a high-rate data-communications system that would allow high-resolution downhole drilling information to facilitate informed drilling decisions in real time and the attendant need to bring data-transmission rates to up to five orders of magnitude from mud-pulse telemetry’s approximate high of 10 bits per second. Evolution of Networked Pipe Networked pipe had its genesis in a program undertaken by Novatek in 1997 to develop a mud-actuated hammer and a unique hammer bit. The company proposed to develop a set of complementary technologies integrated into the mud hammer that would enable various functionalities of the bit, including: 1) downhole bit rotation, 2) sensing and control, 3) data transmission, and 4) directional-drilling capability. In the case of data transmission, the company concluded that a much higher data bandwidth was needed by the oil and gas industry than could be delivered by either existing mud-pulse telemetry or a new hammer acoustic-telemetry system. This was particularly true when considering the need for real-time data to support seismic while drilling (SWD), another possible offshoot of the hammer development. With this conclusion in mind, other acoustic sources with higher frequency ranges than the hammer were investigated. Substantial project focus was directed to this area of R&D, as it was deemed to be a critical enabling technology for the rest of the drilling system under development. Initial development focused on the use of acoustic transmissions to carry high-frequency data through a single length of standard drillpipe. Data-rate limitations led to the abandonment of the concept and to the investigation of wired pipe that transmitted data across the tool joints using high-frequency acoustic transducers. However, the need for electric power and electronic support for each transducer, and the need for timing of the threaded connections when made up, led to the abandonment of that approach also. The company then directed its focus to fundamental work performed with a high-efficiency inductive-coupling sys-tem that looked promising. That technology resulted in networked drillpipe.

Performance of staged and non-staged up-flow anaerobic sludge bed (USSB and UASB) reactors treating low strength complex wastewater

The use of anaerobic processes to treat low-strength wastewater has been increasing in recent years due to their favourable performance-costs balance. For optimal results, it is necessary to identify reactor configurations that are best suited for this kind of application. This paper reports on the comparative study carried out with two high-rate anaerobic reactor systems with the objective of evaluating their performances when used for the treatment of low-strength, complex wastewater. One of the systems is the commonly used up-flow anaerobic sludge blanket (UASB) reactor. The other is the up-flow staged sludge bed (USSB) system in which the reactor was divided longitudinally into 3, 5 and 7 compartments by the use of baffles. The reactors (9 l) were fed with a synthetic, soluble and colloidal waste (chemical oxygen demand (COD) < 1000 mg/l) and operated at 28 degrees C and 24 h hydraulic retention time. Intermediate flow hydraulics, between plug-flow and completely-mixed, in the UASB and 7 stages USSB reactors allowed efficient degradation of substrates with minimum effluent concentrations. Low number of compartments in the USSB reactors increased the levels of short-circuiting thus reducing substrate removal efficiencies. All reactors showed high COD removal efficiencies (93-98%) and thus can be regarded as suitable for the treatment of low strength, complex wastewater. Staged anaerobic reactors can be a good alternative for this kind of application provided they are fitted with a large enough (> or =7) number of compartments to fully take advantage of their strengths. Scale factors seem to have influenced importantly on the comparison between one and multi staged sludge-bed reactors and, therefore, observations made here could change at larger reactor volumes.

Turbo processing in systems with high-efficient space-time coding

Construction principles for algorithms intended to perform space-time and turbo processing of signals and to improve the qualitative characteristics of high-rate data transmission systems have been discussed. The algorithm for space—time processing of signals transmitted by the system with several transmitting and several receiving antennas—which relies on the analysis of principles applied to the construction of known transmission systems with high spectral efficiencies and makes it possible to enhance the reliability of information transmission without deteriorating the system throughput—is proposed. A new iterative algorithm for signal processing at the receiver has been developed to implement the advantages of the proposed method of space—time processing of signals. The results of computer simulation that confirm the great potentiality of proposed algorithms are presented.

Study of Design Method of Optimal Operation Conditions of High-Rate Filtration System

Study of Design Method of Optimal Operation Conditions of High-Rate Filtration System

A New Approach to Evaluating the Performance of a High-Rate IFAS Treatment System

A New Approach to Evaluating the Performance of a High-Rate IFAS Treatment System

Transition Metal Homeostasis.

This chapter focuses on transition metals. All transition metal cations are toxic-those that are essential for Escherichia coli and belong to the first transition period of the periodic system of the element and also the "toxic-only" metals with higher atomic numbers. Common themes are visible in the metabolism of these ions. First, there is transport. High-rate but low-affinity uptake systems provide a variety of cations and anions to the cells. Control of the respective systems seems to be mainly through regulation of transport activity (flux control), with control of gene expression playing only a minor role. If these systems do not provide sufficient amounts of a needed ion to the cell, genes for ATP-hydrolyzing high-affinity but low-rate uptake systems are induced, e.g., ABC transport systems or P-type ATPases. On the other hand, if the amount of an ion is in surplus, genes for efflux systems are induced. By combining different kinds of uptake and efflux systems with regulation at the levels of gene expression and transport activity, the concentration of a single ion in the cytoplasm and the composition of the cellular ion "bouquet" can be rapidly adjusted and carefully controlled. The toxicity threshold of an ion is defined by its ability to produce radicals (copper, iron, chromate), to bind to sulfide and thiol groups (copper, zinc, all cations of the second and third transition period), or to interfere with the metabolism of other ions. Iron poses an exceptional metabolic problem due its metabolic importance and the low solubility of Fe(III) compounds, combined with the ability to cause dangerous Fenton reactions. This dilemma for the cells led to the evolution of sophisticated multi-channel iron uptake and storage pathways to prevent the occurrence of unbound iron in the cytoplasm. Toxic metals like Cd2+ bind to thiols and sulfide, preventing assembly of iron complexes and releasing the metal from iron-sulfur clusters. In the unique case of mercury, the cation can be reduced to the volatile metallic form. Interference of nickel and cobalt with iron is prevented by the low abundance of these metals in the cytoplasm and their sequestration by metal chaperones, in the case of nickel, or by B12 and its derivatives, in the case of cobalt. The most dangerous metal, copper, catalyzes Fenton-like reactions, binds to thiol groups, and interferes with iron metabolism. E. coli solves this problem probably by preventing copper uptake, combined with rapid efflux if the metal happens to enter the cytoplasm.

Effects of Carrier Frequency Offset and Channel Estimation Errors on the Performance of MIMO-OFDM Systems in Spatially Correlated Channels

As an effective technique for combating multipath fading and for high-bit-rate transmission over wireless channels, orthogonal frequency division multiplexing (OFDM) is extensively used in high-rate wireless communication systems, such as, the wireless local area network (WLAN) and the digital television terrestrial broadcasting (DTTB) systems, to support high performance bandwidth-efficient multimedia services. Multiple antennas and transmit or receive diversity, multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM), can be used to improve error performance and capacity of wireless systems. In this paper, we consider the effects of carrier frequency offset and channel estimation errors on the performance of MIMO-OFDM systems in spatially correlated channels. Theoretical calculations and computer simulations are done to analyze the performance degradation of MIMO-OFDM systems in spatially correlated channels due to carrier frequency offset and channel estimation errors, and the theoretical and simulated results match well.

Anaerobic treatment of winery wastewater in fixed bed reactors

The treatment of winery wastewater in three upflow anaerobic fixed-bed reactors (S9, S30 and S40) with low density floating supports of varying size and specific surface area was investigated. A maximum OLR of 42 g/l day with 80 +/- 0.5% removal efficiency was attained in S9, which had supports with the highest specific surface area. It was found that the efficiency of the reactors increased with decrease in size and increase in specific surface area of the support media. Total biomass accumulation in the reactors was also found to vary as a function of specific surface area and size of the support medium. The Stover-Kincannon kinetic model predicted satisfactorily the performance of the reactors. The maximum removal rate constant (U(max)) was 161.3, 99.0 and 77.5 g/l day and the saturation value constant (K(B)) was 162.0, 99.5 and 78.0 g/l day for S9, S30 and S40, respectively. Due to their higher biomass retention potential, the supports used in this study offer great promise as media in anaerobic fixed bed reactors. Anaerobic fixed-bed reactors with these supports can be applied as high-rate systems for the treatment of large volumes of wastewaters typically containing readily biodegradable organics, such as the winery wastewater.

Iterative Irregular Sphere Detection in High-Rate Downlink SDMA Systems

Downlink spatial division multiple-access (DL-SDMA)-assisted multiuser transmission (MUT) employing linear dispersion codes (LDCs) is proposed for space-time signaling, which attains a high diversity order and may support a high-rate data transmission. However, a potentially high complexity may be imposed by the signal detection when aiming to achieve optimum maximum-likelihood (ML) performance. Hence, a novel irregular sphere detection (IrSD) design is proposed to maintain an infinitesimally low bit error rate (BER) at the lowest possible iterative decoding complexity. Quantitatively, in the specific scenario, when six 4-quadratic-amplitude-modulated (QAM) data symbol streams were transmitted by the DL-SDMA system, the full-search-based ML detector had to evaluate all 46 = 4096 possible decision candidates. By contrast, when searching through a fraction of this space, the proposed IrSD may reduce the complexity by three orders of magnitude, quantified in terms of the number of add-compare-select (ACS) arithmetic operations, namely, from the order of 108 to about 105 at E b/N 0 = 5 dB, and still approach the ML performance.

Upflow anaerobic clarification tank (UACT) to upgrade existing anaerobic effluents

The Upflow Anaerobic Clarification Tank (UACT) is of interest as a post-treatment step for high-rate anaerobic wastewater treatment systems. The UACT contributes to extra capture of methane from the raw wastewater. It also significantly facilitates the reuse of the treated water. The efficiency of the UACT process is demonstrated in this study using laboratory-scale reactors. The water produced by the UACT had a low total COD, in most cases below 145 mg/L and a soluble COD below 60 mg/L at surface loading rates between 0.1-0.4 m(3)/(m(2) h) and hydraulic retention times between 5-6 h. The sludge bed of the UACT was characterised by 6-10 times higher substrate affinity (for ethanol, acetate and propionate) compared to the parent UASB and similar specific activity. The results suggest that a UASB followed by the UACT can, upon subsequent application of a rapid filtration, qualify as a total COD removal, no longer necessitating aerobic treatment.

Dynamic material properties of the human sclera

As a result of trauma, approximately 30,000 people become blind in one eye every year in the United States. A common injury prediction tool is computational modeling, which requires accurate material properties to produce reliable results. Therefore, the purpose of this study was to determine the dynamic material properties of the human sclera. A high-rate pressurization system was used to create dynamic pressure to the point of rupture in 12 human eyes. Measurements were obtained for the internal pressure, the diameter of the globe, the thickness of the sclera, and the changing coordinates of the optical markers using high-rate video. A relationship between true stress and true strain was determined for the sclera tissue in two directions. It was found that the average maximum true stress was 13.89±4.81MPa for both the equatorial and meridional directions, the average maximum true strain along the equator was 0.041±0.014, and the average maximum true strain along the meridian was 0.058±0.018. Results show a significant difference in the maximum strain in the equatorial and meridional directions (p=0.02). In comparing these data with previous studies, it is concluded that the human sclera is both anisotropic and viscoelastic. The dynamic material properties presented in this study can be used for advanced models of the human eye to help prevent eye injuries in the future.

High-Rate Internal Pressurization of Human Eyes to Predict Globe Rupture

To determine the dynamic rupture pressure of the human eye by using an in vitro high-rate pressurization system to investigate blunt-impact eye injuries. Internal pressure was dynamically induced in the eye by means of a drop-tower pressurization system. The internal eye pressure was measured with a small pressure sensor inserted into the eye through the optic nerve. A total of 20 human eye tests were performed to determine rupture pressure and characterize rupture patterns. The high-rate pressurization resulted in a mean (SD) rupture pressure of 0.97 (0.29) MPa (7275.60 [2175.18] mm Hg). A total of 16 eyes ruptured in the equatorial direction, whereas 4 ruptured in the meridional direction. There was no significant difference in the rupture pressure between the equatorial and meridional directions (P= .16). As the loading rate increases, the rupture pressure of the human eye increases. Eye injuries are expensive to treat, given that the estimated annual cost associated with adult vision problems in the United States is $51.4 billion. Determining globe rupture properties will establish injury criteria for the human eye to prevent these common yet devastating injuries.

Quantitative and qualitative analysis of methanogenic communities in mesophilically and psychrophilically cultivated anaerobic granular biofilims

Anaerobic granulation describes the self-immobilisation of methanogenic consortia into dense, particulate biofilms. This procedure underpins the operation of several categories of high-rate anaerobic wastewater treatment system. Full-scale anaerobic granular sludge plants have been generally operated in the mesophilic (20–45 °C) or thermophilic (45–65 °C) temperature range. On the other hand, recent studies highlighted the economic advantages of treating wastewaters at their discharge temperatures (mostly under 18 °C), removing a costly heating process and increasing net biogas yield. However, as yet, relatively little information is available about the microbial behaviour and interactions in anaerobic granular sludge formed under psychrophilic conditions. To this end, and in order to provide a microbial insight into low-temperature anaerobic granulation, we monitored the changes in methanogenic community structure, associated with the changes in process performance. Three, laboratory-scale, expanded granular sludge bed (EGSB) bioreactors treating a synthetic glucose wastewater were tested at two temperatures of 37 ± 1 °C (R1) and 15 ± 1 °C (R2 and 3). Quantitative real-time PCR and specific methanogenic activity assays highlighted a community shift towards hydrogenotrophic methanogens, particularly the order Methanomicrobiales in the low-temperature bioreactors. Corresponding to this, denaturing gradient gel electrophoresis (DGGE) analysis identified the emergence and maintenance of a Methanocorpusculum-like organism. Our results indicate that hydrogenotrophic methanogens, particularly the Methanomicrobiales-related populations, are likely to play important roles in low-temperature anaerobic granular sludge systems. This suggests that the process efficiency could be improved by facilitating the growth and retention of this group.

Speckle elimination using shift-averaging in high-rate holographic projection

Speckle is a major source of noise in holographic projection. Time averaging of multiple holograms may be used to reduce speckle contrast, but multiple holograms must be calculated per each frame, costing in computational power. We show that a single hologram may be used to generate a fully speckle-free reconstruction, by cyclic shifting and time averaging. We demonstrate the concept experimentally, and discuss its application for high-rate holographic projection systems.

Sulfate Reduction at pH 5 in a High-Rate Membrane Bioreactor: Reactor Performance and Microbial Community Analyses

High rate sulfate reduction under acidic conditions opens possibilities for new process flow sheets that allow the selective recovery of metals from mining and metallurgical waste and process water. However, knowledge about high-rate sulfate reduction under acidic conditions is limited. This paper investigates sulfate reduction in a membrane bioreactor at a controlled pH of 5. Sulfate and formate were dosed using a pH-auxostat system while formate was converted into hydrogen, which was used for sulfate reduction. Sulfide was removed from the gas phase to prevent sulfide inhibition. This study shows a high-rate sulfate-reducing bioreactor system for the first time at pH 5, with a volumetric activity of 188mmol SO(4)(2-)/I/d and a specific activity of 81mmol SO(4)(2-) volatile suspended. The microbial community at the end of the reactor run consisted of a diverse mixed population including sulfate-reducing bacteria.

Biological breakdown of denitrifying sulfide removal process in high-rate expanded granular bed reactor

This work conducted a denitrifying sulfide removal (DSR) test in an expanded granular sludge bed (EGSB) reactor at sustainable loadings of 6.09 kg m(-3) day(-1) for sulfide, 3.11 kg m(-3) day(-1) for nitrate-nitrogen, and 3.27 kg m(-1) day(-1) for acetate-carbon with >93% efficiency, which is significantly higher than those reported in literature. Strains Pseudomonas sp., Nitrincola sp., and Azoarcus sp. very likely yield heterotrophs. Strains Thermothrix sp. and Sulfurovum sp. are the autotrophs required for the proposed high-rate EGSB-DSR system. The EGSB-DSR reactor experienced two biological breakdowns, one at loadings of 4.87, 2.13, and 1.82 kg m(-3) day(-1); reactor function was restored by increasing nitrate and acetate loadings. Another breakdown occurred at loadings of up to 8.00, 4.08, and 4.50 kg m(-1) day(-1); the heterotrophic denitrification pathway declined faster than the autotrophic pathway. The mechanism of DSR breakdown is as follows. High sulfide concentration inhibits heterotrophic denitrifiers, and the system therefore accumulates nitrite. Autotrophic denitrifiers are then inhibited by the accumulated nitrite, thereby leading to breakdown of the DSR process.

Development of a Practical High-Rate CVD System

We have developed a new chemical vapor deposition (CVD) system that is capable of a high growth rate of over 100 µm/h with good uniformities of thickness and carrier concentration. In this CVD system, the process gases contribute efficiently to epitaxial growth. In a demonstration of the abilities of the CVD system, we achieved an average growth rate of 140 µm/h, a thickness uniformity of 3.9%, and a carrier concentration uniformity of 8.9% in a 2-inch wafer, without degradation of the crystallinity.

Novel interference cancellation methods for BS-CDMA in uplink broadband mobile communication systems

A single-carrier block-spread CDMA (BS-CDMA) system was proposed to offer multi-user interference (MUI) robustness and complexity reduction. However, perfect MUI elimination in BS-CDMA requires channels to be stationary within the block spreading duration which is not always applicable in high-rate mobile communication system. This letter proposes two novel interference cancellation methods to reduce the MUI arising from such scenario by using mobility condition to determine the detection ordering. Simulation results show that the proposed techniques offer significant performance improvement in a realistic multi-user multi-path environment.

Anaerobic digesters as a pretreatment for constructed wetlands

The most commonly used pretreatment technologies for constructed wetland (CW) treatment of domestic sewage are septic tanks (ST) and Imhoff tanks (IT). These technologies have frequently suffered from failures and even in normal operation they offer insufficient removal of solids. As a result, combined ST-CW or IT-CW can experience substrate clogging, especially when high organic loads are applied. In the last 7 years, the operation of combined systems using high-rate anaerobic digesters as a pretreatment and CW as a post-treatment has been reported. A review of the literature indicates that CW in these combined systems operates with a similar organic loading rate (on a chemical oxygen demand basis) but with a lower total suspended solid (TSS) loading rate. In these combined systems, the TSS loading rate is 30–50% less than that applied in CW combined with classical pretreatment technologies. A low TSS loading rate could prevent substrate clogging in CW. This work presents the results of different case studies on the treatment of municipal wastewater with high-rate anaerobic systems. Our interest is focused on the capacity of these systems for removing suspended solids, and therefore on their potential as an appropriate pretreatment to avoid clogging in constructed wetlands and to improve efficiency. Average and 95 percentile TSS concentrations of anaerobic treated wastewater were below 60 and 100 mg/l, respectively, for all configurations. Therefore, the use of high rate anaerobic systems as a pretreatment for constructed wetlands could delay gravel bed clogging. Furthermore, according to the level of organic matter removal, anaerobic pretreatment provided a 30–60% reduction in the required wetland area. Both treatment alternatives can be combined to develop low-cost, robust, and long-term systems for treating municipal wastewater.